Process of fireproofing fibrous materials.



' UNITED STATES PATENT OFFICE.

ROBERT E. ramcn, or MADISON, WISCONSIN,

DEDICATED, BY MESNE ASSIGNMENTS,

TO THE GOVERNMENT OF THE UNITED STATES AND TO THE PEOPLE OF THE UNITEDPatented Feb. 20, 1917.

STATES.

PROCESS OF FIREPROOFING FIBBOUS MATERIALS.

-1 216,729 Specification of Letters Patent. No Drawing. Applicationfiled November 25, 1916. Serial No. 133,475.

(DEDICATED TO THE PUBLIC.)

To all whom it may concern:

Be it known that 1, ROBERT E. PmNoma citizen of the United States ofAmerica, residing at Madison, in the county of Dane, State ofWVisconsin, whose post-oflice address is Madison, Visconsin, haveinvented a new and useful Process of Fireproofing Fibrous Materials.

This application is made under the act of March 3, 1883, chapter 143 (22Stat. 625), and the invention herein described and claimed, may be usedby the Government-of the United States or any of its ofiicers oremployees, in the prosecution of work for the Government, or any personin the United States, without payment to me of any royalty thereon.

My invention relates to a process for treating Wood and other fibrousmaterials, whereby the inflammability of the fibrous materials ismaterially decreased. The object of my invention is to provide a simpleprocess for treating fibrous materials so as to render them immune toany leaching action which might destroy the fireproofing treatment.

In practising my invention the fibrous materials to be treated arehermetically sealed in a retort and surrounded by the treating solutionat or above atmospheric pressure, or they may be placed in open vats ortanks and covered with the treating solution at atmospheric pressure. Myinvention consists largely in injecting into the fibrous material twodifferent substances, hereinafter specified, at different times. It isimportant that the charge be thoroughly dried between injections. Thetreating solution, in one case, will be either a solution of boric acidor any soluble borate, biborate, or perborate. The treating solution, inthe second case, will be of any soluble salt of zinc, lead, aluminum, orcopper, the object being to precipitate into the, wood an insolubleborate,

biborate, or perborate of either zinc, lead, aluminum, or copper, as thecase maybe.

The advantages derived in fireproofin Wood with the described materialsare: (1%

that the substance precipitated in the wood is of an insoluble natureand will not be washed or leached from the wood; and (2) that thesubstance precipitated in the wood is a fusible compound, and when thewood containing this fusible compound is subjected to temperatures highenough to cause distillation of the Wood the compound contained in thewood fuses and causes a coating on the v 10d fiber which protects it andrenders it resistant to fire.

The strength of the solutions used varies with the character of woodtreated. Some species, like pine, which are easily treated, permit ofthe use of more dilute solutions than certain other species, such as redoak, which are diflicult to treat. The strength of the second solutionused should be just suflicient to produce complete chemical change, thusleaving no unchanged zinc chlorid or sodium borate in the wood. If it isdesired to preserve the wood against decay, as well as to render it fireretardent, an excess of zinc chlorid solution may be used.

'Having thus claim:

A process of fire-proofing fibrous material consisting in saturating thefibrous material with a solution of a soluble compound of boric oxid,then drying the material, and then subjecting the dried material to asecond saturation with a soluble salt of lead.

In testimony whereof, I aflix my signature in the presence of twosubscribing witnesses.

described my invention, 1

ROBERT E. PRINCE.

I. E. does.

